Membrane filtration technology has been widely used for liquid purification. However, fouling can become a problem in membrane filtration processes, even if the feed liquid is pre-treated to remove potential foulants. Fouling is a process that results in a decrease in performance of a membrane, caused by the deposition of suspended or dissolved solids on the external membrane surface, on the membrane pores, or within the membrane pores. To reduce fouling, the surface of the membrane may be chemically cleaned, or the system may be flushed periodically to remove foulants on the membrane surface.
In some applications, the surface of the membrane can be chemically modified to reduce fouling. In one example, the surface of the membrane is made more hydrophilic, which can limit hydrophobic interactions between the membrane and some types of foulants. Several materials have been adopted to modify the surface of filtration membranes to increase their hydrophilicity, such as nanoparticles, enzymes and polymers. Various surface modification strategies have been investigated including, for example, blending, surface grafting and surface coating.